Evidence-based practice statistics worksheet with answers

Free printable Evidence-based practice statistics worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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Name: ____________________   Date: ____________

1.Easy
testdisease presentdisease absenttotalpositive77490567abnegative3870873cdtotal8013601440

Practice exercise (made-up values, not clinical guidance). A new test was compared with the reference standard in a study (see the 2 × 2 table). Find the sensitivity Se as a percentage. Round to one decimal place.

a = 77b = 490c = 3d = 870
Se = %
2.Easy
testdisease presentdisease absenttotalpositive31459490abnegative1910711090cdtotal5015301580

Practice exercise (made-up values, not clinical guidance). A new test was compared with the reference standard in a study (see the 2 × 2 table). Find the negative predictive value NPV as a percentage. Round to one decimal place.

a = 31b = 459c = 19d = 1071
NPV = %
3.Medium
casescontrolsexposed48191abnot exposed12199cd

Practice exercise (made-up values, not clinical guidance). A case-control study compares 60 patients with a disease (cases) and 390 people without it (controls). The table shows how many in each group were exposed to a risk factor. Find the odds ratio OR for the exposure. Round to two decimal places.

a = 48b = 191c = 12d = 199
OR =
4.Medium
eventno eventtotaltreatment1882100abcontrol115365480cd

Practice exercise (made-up values, not clinical guidance). In a randomised trial, 100 patients received a new treatment and 480 received the control treatment. The table shows how many in each group had the outcome (an unwanted event such as a stroke). Find the number needed to treat NNT to prevent one event. Round up to a whole number of patients.

treatment: 18/100control: 115/480
NNT =
5.Hard
CER14%EER?RRR 14%

Practice exercise (made-up values, not clinical guidance). A treatment reduces the risk of an event by 14% in relative terms (RRR = 14%). In a patient group the risk without treatment (CER) is 14% over five years. Find the number needed to treat NNT for five years to prevent one event. Round up to a whole number of patients.

RRR = 14%CER = 14%
NNT =
6.Hard
CER3%EER?RRR 48%

Practice exercise (made-up values, not clinical guidance). A treatment reduces the risk of an event by 48% in relative terms (RRR = 48%). In a patient group the risk without treatment (CER) is 3% over five years. Find the number needed to treat NNT for five years to prevent one event. Round up to a whole number of patients.

RRR = 48%CER = 3%
NNT =

Answer key

  1. 1. Se = 96.3 %
  2. 2. NPV = 98.3 %
  3. 3. OR = 4.17
  4. 4. NNT = 17
  5. 5. NNT = 52
  6. 6. NNT = 70

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